Advanced Materials Research Vol. 1183

Abstract: In this paper, the mechanical, elastic, electronic and optical properties of thallium based-perovskites TlSnX₃ (X = F, Cl, Br and I) were investigated using the first-principles calculations. The elastic parameters calculations show that the perovskites are ductile, anisotropic, and mechanically stables. The cohesive energy calculations indicate that the evaluated perovskites are thermodynamically stable. Moreover, the band calculations with HSE06 method reveal that all perovskites TlSnX₃ (X = F, Cl, Br and I) present a semiconductor feature. Further, the optical properties such as reflectivity, refractive index, extinction and absorption coefficients have been calculated and compared for all perovskites compounds. Interestingly, the found results show that the absorption coefficient α(ω) in the visible and infrared regions reaches high values of 1.02, 1.19, 1.14 and 1.03 × 10⁶ cm^-1 for TlSnI₃, TlSnBr₃, TlSnCl₃ and TlSnF₃ , respectively. These results suggest that the heavy thallium perovskites TlSnX₃ (X = F, Cl, Br and I) have potential for optoelectronic applications.

Abstract: Thermoelectric materials are useful for various application in daily life. Their application such as sensors, generators and electronic components, making thermoelectric materials widely studied. Antiperovskite compounds that can have semiconducting behaviour is probable candidate for thermoelectric materials. In this article, thermoelectric properties of anti-perovskite X₃SiO (X = Sr and Ba) were investigated using density functional theory (DFT) method and Boltzmann Transport Equations (BTE). Electronic properties such as band structure, partial density of states were computed using the generalized gradient approximation with Perdew-Burke-Ernzerhof (GGA-PBE) functional in CASTEP code. The thermoelectric properties such as Seebeck coefficient, electrical conductivity, and power factor are calculated using BoltzTraP code that utilised BTE. The calculated band structures of Ba₃SiO and Sr₃SiO show that these compounds having semiconductor behaviour with direct band gap of 0.44 and 0.43 eV respectively at Γ-Γ k-point. It was found that Ba₃SiO is a better candidate for thermoelectric materials due to its higher Seebeck coefficient (-4.90 10^-4 V/K) at room temperature compared to calculated Seebeck coefficient (-5.84 10^-4 V/K) of Sr₃SiO. The power factor value of Ba₃SiO which is 2.96 x 10^-4 W/mK² is also higher compared to power factor of Sr₃SiO at 7.12 x 10^-7 W/mK² at room temperature.

Abstract: The synthesis of Cd_0.5Zn_0.5S/PVP and Cr_x: Cd_0.5-xZn_0.5S/PVP(x = 0.02, 0.04, 0.06, 0.08) nanoparticles were carried out using a chemical co-precipitation reaction using homogeneous solutions of cadmium, zinc and chromium salts. The impact of Cr doping on the morphological, structural, and optical characteristics of nanoparticles was investigated in this study. Energy dispersive analysis of X-rays (EDAX), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Diffuse Reflectance spectroscopy (DRS) have been utilized to examine the structural, optical, and morphological properties of elements. EDAX analysis verified the existence of chromium (Cr) within the cadmium zinc sulphide (CdZnS) crystal structure. The XRD analysis revealed that the Cr doped CdZnS nanoparticles exhibited crystallization in the zincblende structure, with a predominant orientation along the (1 1 1) plane. The nanoparticles have an average size ranging from 3 to 6 nm. The particle size determined from the SEM images corresponded with the findings from the XRD analysis. The DRS revealed that the increase in Cr concentration caused a shift of the absorption edge towards lower wavelengths. The bandgap energy estimates ranged from 3.85 to 4.05 eV. The blueshift is caused by the quantum confinement phenomenon.

Abstract: Cassava peels (CP) are agricultural-industrial co-products, better means of generating wealth that have recently attracted the attention and efforts of scientists due to their vitality in achieving a higher standard of living in a variety of industrial applications and human health care. Hence, an urgent demand for low-cost, non-toxic nanostructure material that can host, deliver, and transmit light with improved optical properties. In this work, β-cyclodextrins (β-CDs) was produced from cassava starch using US132 Cyclodextrins glucanotransferase enzyme (CGTase), converting it to cyclic oligosaccharides using experimental designs. The β-CDs produced by US132 CGTase are subsequently refined to a high level (67.26 g L-1) and homogenized using an eco-friendly, straightforward crystallization process that yielded a 40% purification yield. Gold nanoparticles (AuNPs) was effectively synthesized from Kahaya senegalenses plant, as a natural reducing agent. The Uv-visible and SEM evaluations revealed the plasmon resonance bands and spherical cap-shaped morphology of the developed hybridized β-CDs/AuNPs. However, the functional groups contained in the developed nanohybrids were validated by the FT-IR analysis. The size and crystallinity of the developed sample was found within the nano range as deduced from XRD and TEM (20-20 nm) analysis. The successful formation the developed nanostructured β-CDs/AuNPs was confirmed employing Uv-Visible, XRD, FT-R and SEM analysis. Therefore, the developed nanostructured β-CDs/AuNPs displayed significant and noticeable advantages which can withstand present drifts, due to its environmental friendliness, biocompatibility and encapsulating effect.

Abstract: DL-valinium maleate [DLVM] compound was grown as single crystals at room temperature by gradual evaporation from an aqueous solution. The classical nucleation theory was examined to maximize the growth conditions for producing high-quality crystals, Nucleation kinetics studies reveal that the crystal has been grown at room temperature 313 K for which predicted critical supersaturation is 6.19. The grown compound DLVM crystallized in a triclinic system with a centrosymmetric space group P1, according to single crystal and powder X-ray diffraction experiments. The lattice parameters were calculated as a= 6.17 Å, b= 9.68 Å, c= 10.59 Å, α= 105.75°, β = 105.67º and γ = 104.69° with unit cell volume 548.2 ų. The presence of functional groups in the grown compound has been identified by using Fourier Transform Infrared [FTIR] experiments. NMR studies were used to examine the structural features of DLVM compounds. Since the grown material belongs to the centrosymmetric space group, the material has been found to exhibit third-order NLO property. The Z-scan technique was used to analyse the third-order nonlinear behaviour of the grown crystal. The technique was very useful in evaluating the nonlinear refractive index n₂, absorption co-efficient β, and nonlinear optical susceptibility χ⁽³⁾ of the grown material. Hence, the grown crystal finds useful applications in optoelectronics. The antibacterial activity of the title compound was also studied by using the Agar disc diffusion method against the standard bacteria Klebsiella pneumonia, Staphylococcus aureus and Enterococcus faecalis. The results of the antibacterial activity experiment show that the synthesized DLVM crystal will be a good option for the creation of antibiotic medicines that will combat the tested bacterial strains.

Abstract: Silicon has an ultra-high theoretical specific capacity, making it an ideal material to replace traditional graphite anodes. However, the volume expansion of silicon leads to its poor cycling stability. In this work, a high-compacted density silicon-carbon anode (PMMA@Si/C) is presented. The structure of poly(methyl methacrylate) (PMMA) mixed with silicon creates a pre-positioned space on the graphite surface, providing room for expansion during silicon cycling. It was also blended with commercial graphite and after carbonization of the surface, a carbon layer was formed using a asphalt coating. At a current density of 0.1 C, the PMMA@Si/C anode has a capacity retention rate of 72.8% after 300 cycles. The compacted density of PMMA@Si/C is 1.65 g/cm³, which is close to that of commercial graphite negative electrodes. And it has excellent rate performance. The preparation method is simple and suitable for mass production. The developed PMMA@Si/C is a promising commercial anode.

Abstract: Biodegradable magnesium alloy WE43 (Mg-4Y-3RE) has received great attention in orthopaedic applications as it can dissolve completely after bone tissue repair, eliminating the need for a second surgery to remove the WE43 implant. However, the rapid degradation of WE43 implants during bone healing remains a concern. Rapid degradation can deteriorate the mechanical strength and generate a significant amount of hydrogen gas via corrosion in physiological environments, negatively affecting bone healing and the surrounding tissues. To overcome the rapid degradation of medical implants, one commonly used method is surface modification via laser surface melting (LSM) to alter the surface microstructures and improve the corrosion resistance. This paper investigates the possibility of applying LSM technique to refine the surface microstructures of WE43 alloy and compares the microstructures induced by LSM with the extruded alloy without laser treatment. Results show significant grain refinement after LSM with average grain size decreased to 3μm as compared to 5μm before LSM, approximately 40% reduction in grain size. Different types of grain morphology are also identified at different locations in the melt pool due to different temperature gradients and cooling rates. It is observed that the depth of the melt pool increases with increasing laser power and decreasing laser scanning speed due to the higher heat input. It is also observed that grain size decreases with decreasing laser power and increasing laser scanning speed due to increased cooling rate. Results from this study show that LSM, a form of rapid solidification processing, can form a predominantly basal crystallographic texture, homogenise and refine the surface microstructures of WE43, which are beneficial for corrosion resistance.

Abstract: Prolonged concrete mixing can occur due to transportation delays or logistical issues on construction sites, potentially affecting the material's properties. This study investigates the effects of extended mixing times on concrete's fresh and hardened properties utilizing four different types of Portland cement: PC-32, PC-40, PC-RS-32, and PC-LF. An experimental program involved materials characterization, concrete mix design, and systematic testing procedures. Fresh concrete properties, including slump, temperature, specific mass, and air content, were evaluated hourly for up to 8 hours of mixing. Hardened concrete tests encompassed electrical resistivity, dynamic modulus of elasticity, and compressive strength measurements. Prolonged mixing led to a significant loss of slump and plasticity, particularly for PC-LF cement. Specific mass and apparent density decreased with mixing time, while electrical resistivity declined hourly, indicating increased porosity and susceptibility to chemical attacks. The dynamic modulus of elasticity remained relatively constant, except for PC-LF cement. Compressive strength was maintained or slightly increased up to 7 hours but decreased for PC-32 and PC-LF cements at 8 hours. The study demonstrates the feasibility of prolonged mixing for up to 8 hours with proper precautions. The choice of cement type played a crucial role, with PC-40 cement exhibiting the best overall performance. Further research is recommended to investigate durability aspects, porosity characteristics, and methods to maintain workability during extended mixing times.

Abstract: Microplastic contamination is a severe environmental problem that must be addressed, especially in developing countries like Pakistan, where there is a dearth of research on its effects on ecosystems and public health. Our initiative suggests an economical and environmentally friendly method for removing microplastic from aquatic habitats, which helps to achieve Sustainable Development Goals (SDGs) 6 (Clean Water and Sanitation) and 12 (Responsible Consumption and Production). For our experiment, we utilized electrocoagulation (EC), an electrolytic method conventionally used for water and wastewater treatment. EC is well-known for producing coagulants in situ that destabilize and agglomerate microplastics. The intrinsic electrochemical reactions of EC further improve particle removal, providing a low-chemical, size-inclusive, and adaptable technique. The current study utilized low-density polyethylene (LDPE) microplastics with a particular size range. Using aluminum electrodes, system optimization was accomplished at 12 volts and 100 rpm. The effectiveness of the EC procedure was evaluated in a pilot trial that removed microplastics up to 94%.